The present invention relates to a drive unit, in particular an internal combustion engine, having a fluid line arrangement, in particular an oil line arrangement, wherein the fluid line arrangement has at least one cavity with a spacer element which ensures the maintenance of a minimum distance between a first wall element and a second wall element of the cavity. The cavity is accessible for a fluid via a bore in the first wall element. The invention also relates to a spacer element for a fluid line arrangement having a cavity adjoined by a first wall element and a second wall element, wherein the first wall element has a bore which leads into the cavity and through which a fluid can flow. The invention also relates to a tool kit for mounting a spacer element.
Drive units, for example internal combustion engines, have fluid line arrangements through which fluids serving, for example, for cooling and/or lubricating the drive unit are conducted. The fluid line arrangement also includes, for example, a hollow camshaft through which the engine oil fluid flows. Various cavities are produced in the camshaft by various wall elements. For example, a stopper at one end of the camshaft forms a first wall element, and an oil cover spaced apart from the stopper forms a second wall element, and therefore a cylindrical cavity is formed between the first wall element and the second wall element in the hollow camshaft. A radial bore through the camshaft wall and an axial bore through the stopper lead into the cavity. Engine oil can flow through the cavity via the bore, and the entire arrangement consequently constitutes a fluid line arrangement. The wall elements can be fastened in various ways. They can, for example, can be screwed in, adhesively bonded in or pressed in. Under the circumstance that a force directed in the direction of the first wall element acts on the second wall element, the position of the second wall element can be fixed by a spacer element which absorbs the force. Drive units provided for mass production and the fluid line arrangements thereof have to be able to be produced cost-effectively and they have to reliably carry out the function thereof by ensuring a minimum distance in a cavity. The spacer element is suitable, inter alia, also for retrofitting. In this case, suitable tools are also required for mounting the spacer element.
It is consequently the object of the present invention to provide a drive unit having a fluid line arrangement with a cavity, which can be produced cost-effectively and which reliably carries out the function thereof; it is also the object of the invention to provide a cost-effective and reliable spacer element for the fluid line arrangement of the drive unit and a tool kit for mounting the spacer element.
These and other objects are achieved by a drive unit of the generic type defined above and by an internal combustion engine, which is characterized in that the fluid line arrangement has a resilient clamping sleeve which can be introduced through the bore, wherein the clamping sleeve has a first length portion which is provided in the bore in a manner remaining in contact with the bore wall, and a second length portion which is set back from the first length portion by at least one notch running transversely with respect to a longitudinal axis of the clamping sleeve. The second length portion is designed as an axially slotted tube, the borders of the slot being curved radially outward, and serves as a spacer element.
The clamping sleeve has approximately the form of a cylindrical shell. The clamping sleeve is divided along a longitudinal axis thereof by a notch into a first length portion and a second length portion. The length portion of the clamping sleeve in which the notch is located is assigned to the first length portion. The first length portion is provided in the bore. By contrast, the second length portion, which has the length of the minimum distance to be maintained, is provided in the cavity as a spacer element.
The clamping sleeve has good mechanical stability because of the partially cylindrical shape thereof and can be produced simply and cost-effectively. The outer circumference of the clamping sleeve can be reduced by pressure against the cylindrical shell walls, and therefore the clamping sleeve can be introduced into the bore of the first wall element and pushed through the bore until only the first length portion is still inserted in the bore and the second length portion extends into the cavity located to the rear of the bore. The second length portion relaxes in the cavity because of the resilient or elastic property of the clamping sleeve, and increases its circumference. Edges, which are formed by the notch, of the borders of the slot of the second length portion engage as a result of the radially outwardly directed elastic relaxation behind surface regions of the first wall element that are located next to the bore. In various exemplary embodiments, the slot borders are curved differently radially outward, for example as a plane running outward tangentially from the cylinder or as a surface which is arched convexly outward in the form of a groove and has a larger radius of curvature than that of the cylinder. By means of the radially outwardly curved slot borders, the clamping sleeve, once introduced and relaxed in the second length portion thereof and therefore fitted, can no longer be pushed back through the bore.
According to an advantageous refinement of the drive unit according to the invention, the clamping sleeve is formed from sheet metal, wherein the sheet metal is composed of stainless steel. Sheet metal can be processed in a simple manner, for example by punching and bending, and therefore, when the starting materials used are sheet metal, the clamping sleeves can be produced simply and cost-effectively. In some exemplary embodiments of the invention, use is made of other suitable starting materials, for example tubes. Steels have good elastic properties which are maintained even at higher temperatures. In addition, stainless steels have a high corrosion resistance, and therefore corrosion, for example due to condensation water which occasionally occurs, does not constitute a problem. However, in some exemplary embodiments, aluminum sheets, nickel sheets or copper sheets are used.
In an advantageous exemplary embodiment of the invention, the first length portion of the clamping sleeve has an axial slot, wherein the diameter of the clamping sleeve is of such a size that the first length portion of the clamping sleeve, which length portion is located in the bore, is compressively stressed. By means of the compressive stressing, the first length portion fits closely against the wall of the bore. As a result, the clamping sleeve is clamped in the bore in a manner free from play. In alternative exemplary embodiments, for example if the clamping sleeve is manufactured from a tube, the first length portion does not have an axial slot.
According to an advantageous aspect of the drive unit according to the invention, outer corners of the slot edges that are located on the outside of the clamping sleeve and in the second length portion are curved radially inward. When the clamping sleeve is introduced into the bore, the inwardly curved slot edges cause the front end of the clamping sleeve to be pointed, and therefore the clamping sleeve can easily be introduced into the bore.
A further advantageous aspect of drive units according to the invention is that the second length portion of the clamping sleeve has perforations through which the fluid can flow. It is always ensured by the slot in the second length portion that the fluid can flow through the cavity, the clamping sleeve and the bore. The perforations bring about a reduction of the flow resistance caused by the clamping sleeve, and therefore the clamping sleeve ultimately no longer presents any significant flow resistance.
In a further advantageous partial aspect of the invention, outer corners of the clamping sleeve are rounded. During the mounting of the clamping sleeve, the round corners reduce the risk of the clamping sleeve being hung up at an edge or the like. Rounded outer corners, past which the fluid flows, for example outer corners located on the notch, are also more advantageous in terms of flow than sharp-edged outer corners.
According to a further advantageous aspect of drive units according to the invention, at least one round internal angle is formed at one end of the notch of the clamping sleeve. During elastic deformation of the clamping sleeve, sharp internal angles are subject to a greater mechanical loading than other parts of the clamping sleeve. By means of the internal angles of rounded design, the risk of material overloading and cracking, which is associated therewith and originates from an internal angle, is reduced.
In yet another advantageous detail of the invention, a protrusion extending into the second length portion is formed at one end of the notch of the clamping sleeve. In the mounted state of the clamping sleeve, the ends of the notches are located on the cavity-side edge of the bore of the first wall element. Punctiform concentrations of mechanical stresses in the clamping sleeve are avoided by the protrusions which extend into the second length portion. In addition, the protrusions constitute perforations through which the fluid can flow.
In a second aspect, the object of the invention is achieved by an internal combustion engine having an oil line arrangement as a concrete form of the generic type mentioned at the beginning, wherein the internal combustion engine has characterizing features of at least one drive unit according to the invention.
In a third aspect, the object of the invention is achieved by a spacer element of the generic type defined at the beginning, which is designed as a clamping sleeve, as is described in conjunction with at least one drive unit according to the invention. This clamping sleeve is a simple and cost-effective component which reliably fulfils the object of the invention.
In a third aspect, the object of the invention is achieved by a tool kit for mounting a spacer element in a drive unit, which tool kit is designed for a spacer element according to the invention and has a prestressing tool and a pressing-in tool, wherein the prestressing tool has a bore which has a diameter which is the same size as or is smaller than the bore in the first wall element, and where the pressing-in tool has a pressing-in cylinder, the diameter of which is of such a size that the pressing-in cylinder can be introduced into the bore of the prestressing tool in a manner substantially free from play.
By using the tool kit according to the invention, particularly simple manual mounting of the clamping sleeve in the drive unit or in the internal combustion engine is possible. The clamping sleeve is provided in a prestressed manner in the bore of the prestressing tool such that the clamping sleeve can be introduced into the bore of the first wall element with or without play and without further compression. The pressing-in cylinder, which can also be a hollow cylinder, can be pushed into the prestressing tool, and therefore the clamping sleeve can be pushed by the pressing-in cylinder through the prestressing tool and through the first wall element. The pressing-in cylinder is designed to be sufficiently stable that the stiction forces produced by the tensioned clamping sleeve can be overcome.
In advantageous refinements of the tool kit according to the invention, the prestressing tool has a clamping sleeve guide tube which can be introduced into the bore of the first wall element, and/or the pressing-in tool has a guide cylinder which can be introduced into a clamping sleeve which is prestressed in the prestressing tool. The clamping sleeve guide tube makes it possible for the prestressing tool to be positioned smoothly and without tilting on the first wall element. The guide cylinder which is arranged concentrically on the pressing-in cylinder guarantees that end edges of the clamping sleeve bear securely against the radial border of the pressing-in cylinder and mutually centered alignment of clamping sleeve, pressing-in cylinder and bore of the prestressing device. The axially rear end of the pressing-in tool, which end lies opposite the guide cylinder located axially at the front can be designed as a contact surface with which the clamping sleeve can first of all be pushed into the prestressing sleeve located on the first wall element before the clamping sleeve is pushed by the pressing-in cylinder, after rotation of the pressing-in tool, further through the prestressing tool and the first wall element.
In a preferred embodiment of the tool kit according to the invention, the prestressing tool and the pressing-in tool have stops. The stops are dimensioned in such a manner that, when the clamping sleeve is correctly fitted, the stop of the prestressing tool strikes against the first wall element and the stop of the pressing-in tool strikes against the prestressing tool. Axial displacement of the clamping sleeve to the correct distance is therefore ensured at the same time as the prestressing tool and pressing-in tool are pushed in fully. The stops are preferably cylindrical with a readily handleable diameter. In an alternative embodiment, instead of the stops, there are merely markings, the position of which is checked visually.
According to an advantageous development of the tool kit according to the invention, the latter has a test gauge for determining the position of the second wall element. The test gauge has a test sleeve and a test pin which is displaceable in the test sleeve and can be pushed completely into the test sleeve when the second wall element is in the correct position. It can be tested with the test gauge, prior to mounting of the clamping sleeve, whether the second wall element is fastened at the correct position and therefore the clamping sleeve can be mounted. The position of the second wall element can alternatively also be determined differently, for example with a measuring gauge. However, the use of the test gauge is preferred since the latter is manufactured at the correct length, and therefore measuring errors, for example due to erroneous reading or skewed introduction, are prevented and the clamping sleeve can ultimately be mounted rapidly.
It is obvious to a person skilled in the art in the field of the invention that the various refinement possibilities which are presented may be combined differently with one another.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.